A week after the earthquake and tsunami struck, donations are running at around a sixth of the level they were following the earthquake in Haiti.

Fund–raisers blamed Japan's status as the world's third biggest economy, as well as competing appeals such as Comic Relief, for the public's comparative reluctance to help.

The American Red Cross said it had raised £29 million for the tsunami appeal, about half the amount it raised after a similar period following the Haiti earthquake.

A significant portion of the money raised in the United States has come from celebrities, including Sandra Bullock, the actress, who became the single biggest donor when she gave $1million (£618,000) to the appeal yesterday.

The singer Lady Gaga raised £150,000 in four hours by selling wristbands via her website, and Charlie Sheen, the actor, is donating $1 per ticket from all of his forthcoming live shows to the appeal.

Corporate donors include the Walt Disney studio, which has given £1.5 million, and Warner Bros, which is giving profits from the sale of DVDs of the Clint Eastwood–directed film Hereafter.

According to one report in the US, donations worldwide are running at one sixth the level they were following the Haiti earthquake, and a quarter the level of donations after Hurricane Katrina in New Orleans.

Fund–raising in Britain has been left to individual charities, including the British Red Cross, Save the Children and Oxfam, after the Disasters Emergency Committee decided not to launch an umbrella appeal for Japan.

Save the Children, which has raised more than £1million for Japan from donors in Britain, said the British public had been "very generous".

The charity said donations to the Japan appeal had been "steady" but "not as high as donations for Haiti".

A spokesman said: "We think it's a lot to do with the fact that perhaps people see Japan as being more able to respond to this sort of thing than poorer countries.

"Having said that, we cover a specialised area focusing on children and British people have shown that they do want to give, for which we are extremely grateful."

The actress Sandra Bullock became the biggest individual donor when she gave $1million for the earthquake victims.